Various types of drip irrigation apparatus are known to be formed of two or more layers of a thermoplastic material, bonded together by heat sealing. A common problem in such apparatus has been the provision of a communication path between the flow conduit and the pressure reducing path and between the pressure reducing path and the outside. According to one prior art technique, such communication paths are formed by laser aperturing. This method, however, requires significant accuracy and introduces complication into the manufacturing process, thus increasing the possibility of rejects and possibly increasing the costs of manufacture.